Messages in this thread | | | Date | Mon, 7 Oct 2013 18:41:56 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH 00/50] tools/perf: Speed up the build system |
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* David Ahern <dsahern@gmail.com> wrote:
> I also noticed that the dwarf test is still run even with the NO_DWARF > option passed in: > > [daahern@nxos-vdc-dev1 perf]$ make O=/tmp/junk LDFLAGS=-static > NO_DWARF=1 -j 4 > BUILD: Doing 'make -j16' parallel build > > Auto-detecting system features: > > ... backtrace: [ on ] > ... dwarf: [ on ] > ... fortify-source: [ on ] > > Note the dwarf test shows 'on'.
Hm, yes.
This is just the print-out though - the actual feature logic should still follow the NO_DWARF=1 setting (modulo bugs).
So I'm wondering, should we solve this by adding extra logic linking the feature flags with their legacy names. It would get unwieldy rather quickly I think.
Another solution would be to introduce a new method to disable features, via something like:
make FEATURE_dwarf=0
Where the pattern would follow the auto-detected naming. This would simplify the printout logic and would simplify the feature support / flags decision tree as well.
Furthermore, it would unify the various flags we have today, which is rather mixed: for example there's NO_DWARF which is a name that shows negated logic, but there's also HAVE_CPLUS_DEMANGLE_SUPPORT is is a name with positive logic. We'd have one uniform naming scheme permeating the whole build system.
And that brings in your [K]config patches: which would make sense in that context as well, as they'd allow the permanent configuration of features with 3 states for each feature flag:
off auto-detect on
Your scheme I think makes a lot of sense on top of my bits. Packagers would likely want to use a .config to build perf, most users would likely be fine with a default of everything on auto-detect. Specialized users would want to use their own .config's.
Thanks,
Ingo
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